Why autumn leaves drop, and what’s that growth on my orchid?

Early cold temperatures -- or an abrupt shift from warm to cold in autumn -- can kill Japanese maple leaves while still on the tree, and they'll likely hold on until spring. Photo Credit: Christine Desmond

DEAR JESSICA: My Japanese maple tree never lost all of its leaves. Is that a bad thing? Is there something I should do?

— Christine Desmond,

Greenlawn

DEAR CHRISTINE: It’s not typical for Japanese maples to hold onto their leaves, while oak and beech trees tend to do this somewhat routinely. I blame the unusual autumn weather we experienced for disturbing your tree’s natural...

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DEAR JESSICA: My Japanese maple tree never lost all of its leaves. Is that a bad thing? Is there something I should do?

— Christine Desmond,

Greenlawn

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DEAR CHRISTINE: It’s not typical for Japanese maples to hold onto their leaves, while oak and beech trees tend to do this somewhat routinely. I blame the unusual autumn weather we experienced for disturbing your tree’s natural leaf-shedding process, which is called “abscission.”

Air roots of Phalaenopsis orchids grow above soil, and the plants use them to cling to trees in their natural jungle habitat. This enables them to position themselves to take advantage of a spot that provides the most sunlight.

Abscission occurs when a chemical reaction weakens small cells at the base of leaves as a tree is preparing to go dormant. When those cells weaken, stems can no longer support the weight of their leaves, and so they detach and drop. But when cold weather hinders the chemical reaction, leaves don’t naturally separate.

October was unseasonably warm on Long Island, with many days having temperatures in the 70s and even 80s. November wasn’t any more seasonally appropriate, with an average temperature of 61 degrees. This, no doubt, delayed dormancy for many plants and trees. Then the mild weather shifted abruptly in mid-December, dropping from mostly 50s and 60s to the 20s and teens in just a matter of days, and remaining there. This didn’t allow much time for plants to realize winter was coming, and the cold killed the leaves before trees could complete the chemical process and separate.

The good news is your tree will be fine.

DEAR JESSICA: I have a beautiful blue orchid that I received for Mother’s Day. My question is what are those long pieces hanging out of the pot? I tried to work them back in, but they break. Is that part of the root? What do I do with them?

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— Patti Carman,

Port Jefferson Station

DEAR PATTI: Those long pieces are indeed roots, and you shouldn’t attempt to remove or cover them with soil. Some orchids, such as the Phalaenopsis I suspect you have, grow a second set of roots, which are different from their below-ground counterparts. These “air” roots remain above soil, and the plant uses them to cling to trees in their natural jungle habitat. This enables them to position themselves to take advantage of a spot that provides the most sunlight.

Although your plant doesn’t have that need, it does use its air root system to absorb moisture and carbon dioxide from the air. Cutting them also would open a wound through which a virus or bacteria can enter. So leave them be, unless they dry up and die, which they may do in dry environments, such as inside your home during winter. In that case, simply cut them away and discard.

DEAR JESSICA: I would like some advice about Montauk daisies. Mine get so big and start falling over and splitting in the middle. Is there any way to stop them from getting so big? And how do you divide them?

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— Mary Falkenberg,

Smithtown

DEAR MARY: Montauk daisies, sometimes called Nippon daisies (Nipponanthemum nipponicum), are shrubby mounding perennials that prefer full sun but can tolerate partial shade and thrive in most soil. Although they grow just 2-3 feet tall, they have a tendency to flop over, especially when they are overgrown.

Cutting them nearly to the ground in May, and by half their regrown size in late June, will encourage a bushier habit that’s less likely to flop. Splitting — growing with an empty hole in the middle of the bush — is an indication it’s time to divide your plants. Doing this every three years will rejuvenate and help plants thrive.

Divide plants in early spring (now) when the soil is moist, such as after a rainfall, or plan ahead and water the area a day in advance. This not only will make the job easier, but will reduce any root damage caused by digging through hard soil.

First, because you are dividing, cut the plant nearly to the ground so you can see what you’re working with. Insert a round-pointed shovel or spading fork into the soil and work your way around the plant to carve a circle around its roots. Then retrace your pattern, rocking your tool to lift up portions of roots all around and under the plant until you can lift it out of the ground. Try to get as much of the root system as possible. Next, using a sharp knife or the flat end of a large spade, slice through the plant and roots, cutting through the center until you have two plants.

Plant half back into its original spot, taking care to keep the roots at the same depth as they had been, and plant the other elsewhere, a minimum of two feet away to allow for growth. If the plant is very large, you can even divide it into three or four pieces.

For a nutritional boost — and to improve drainage — it’s a good idea to mix compost into the backfill. Tamp down the soil and water well after planting.